Hello Ronnie from scotland, happens to me too, have went up to do a couple of numbers in pub, and have just went to pieces, shakes memory loss etc luckily I play the blues and just talk nonsense over the easy blues chords. anyway Clapton said one time that playing in pubs you only get the punters attention for a minute or so per number as opposed to a concert where everyone is listening with intent, so keep at it they can't shoot you for it, and remember the object is to ENJOY
best of luck Ronnie